The present invention relates to a personnel lift and, more particularly, to a portable lift machine including a work platform raised and lowered by a lifting system. The LiftPod® system by JLG Industries, Inc. has been described in U.S. patent application Ser. No. 10/594,666, U.S. patent application Ser. No. 11/581,785, U.S. patent application Ser. No. 12/190,217, U.S. patent application Ser. No. 12/293,759, U.S. patent application Ser. No. 13/191,676, U.S. Pat. No. D570,071, U.S. Pat. No. 7,614,459, U.S. Pat. No. 7,762,532, and U.S. Pat. No. 7,766,750. See also www.LiftPod.com. The contents of the referenced documents are incorporated by reference.
The ladder concept is several thousand years old. Existing ladders, however, can be cumbersome and difficult to maneuver. Additionally, conventional ladders can be unstable particularly on uneven ground, and a work area is limited to the user's reach.
Ladder companies are reluctant to develop powered mechanical products. It would be desirable, however, to develop a personnel lift that achieves many of the advantages of a ladder, e.g., can be set up and used by a single operator, lightweight, etc., while providing for greater stability and a larger working area in a portable powered machine.
Mast climbing platforms are known and typically include a mast that can be free-standing or supported by a wall or other support structure. However, existing mast climbers have minimum SWL loads of 1000 lbs and are not portable or operable by a single user due at least to their size. Vertical mast products and aerial work platforms include a moving platform and generally are also typically too large for portability and are very far from the many advantages provided by a ladder in terms of portability, low cost and ease of use.
To achieve portability, a light weight, reliable lift system mechanism is desirable to provide the functionality expected of a device which lifts personnel.